A shortage of seasonal workers may result in rotten crops and lost profits in Northern Ireland, as industry insiders say the Government needs to allow non-EU workers into the UK.

Workers from Eastern Europe are said to be choosing to stay on the Continent as the implications of Brexit, a weak pound and high travel costs to the UK take their toll.

Shane Donnelly, one of the directors at Donnelly Horticulture near Maghery in Co Armagh, which supplies supermarkets with lettuce and cut flowers, said keeping labour is becoming more difficult.

"We have some people who are going back home to Bulgaria again, and we're finding it hard trying to get people to replace them," he said.

Mr Donnelly said his company is behind with planting at the moment. "We are able to get our stuff picked, but we're not able to get enough stuff planted ... that's one downfall at the moment of some people leaving, as such, and of not being able to replenish your staffing requirements," he added.

Mr Donnelly said the shortage of workers is as much an issue in Northern Ireland and the Republic as it is in Britain.

Stephanie Maurel (above), chief executive of Concordia, which supplies around 10,000 foreign workers to 200 farms in the UK each year, said the company could be 10% short this year, adding that, nationally, the picture will be "a lot, lot worse".

"It's compounding the misery for growers who are planting, and literally they are looking out of their windows not knowing if they're going to have enough workers to harvest and gather in the crops and the fruit," she said.

She added that up to five offers are being put to each seasonal worker but large numbers are not accepting. "The money itself is reasonable, and that doesn't come out as a complaint when we do our surveys and focus groups. What does is that the strength of the pound means that when they convert back into euro and to local currency they're usually better off going to Germany or Scandinavia, because Brexit has actually had an impact on the comparison rates, which is one thing," she revealed.

Ms Maurel said the cost of travel is another issue, with flights from Bulgaria or Romania to Scotland costing up to £250.

And Eastern European countries also now offer a lot more opportunities than they once did.

As well as rotten crops, there are many other consequences to deal with due to a shortage of seasonal workers, such as businesses going bust, farms going into administration and a hit on investing in farms.

Ms Maurel said the Government needs to give the go-ahead to recruit workers outside the EU.

"It's not an immigration issue. It's an agriculture issue," she said.

Alison Capper, a farmer who is chair of the National Farmers Union horticulture and potatoes board, said the consequences of a shortage will be wasted crops and lost revenue and profit, and potentially empty shelves in supermarkets. She said anecdotally it seems growers "have just about enough labour", but that the industry is "very concerned" about the summer months.

"What we've seen happening since the referendum, sterling's devalued, that's one reason. We're not as attractive a place to come and work."

A Government spokesman said: "Defra and the Home Office are working closely to ensure the labour needs of the agriculture sector are met once we leave the EU. We have been clear that up until December 2020, employers in the agricultural and food processing sectors will be free to recruit EU citizens to fill vacancies and those arriving to work will be able to stay in the UK afterwards."